By injecting fluorescent green protein into embryonic pigs, a research team at the island's leading National Taiwan University managed to breed three male transgenic pigs, said professor Wu Shinn-Chih of the university's Institute and Department of Animal Science and Technology.

"There are partially fluorescent green pigs elsewhere, but ours are the only ones in the world that are green from inside out. Even their hearts and internal organs are green," Wu said on Thursday.

In 2003, a Taiwan company began selling the world's first genetically engineered fish, sparking protests by environmentalists who said the fluorescent green fish posed a threat to the earth's ecosystem.